<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* h2 {
            color: red;
        }
        .box1 {
            color: red;
        } */

        h2, .demo{
            color: red;
        }
    </style>
</head>

<body>
    <h2>二级标题</h2>
    <div>
        <ul>
            <li><p>box1 li content</p></li>
            <li><p class="demo">box1 li content</p></li>
            <li><p>box1 li content</p></li>
            <li><p>box1 li content</p></li>
        </ul>
        <p>box1 content</p>
    </div>
</body>
</html>